Electric discharge device of the indicator type



C. H. BACHMAN Nuv. L 1949 Filed 001.- 7, 1944 Fig.5.

am m d m a e I O C M t a O n Z w a A Ti Mm P I a N y y b p w 3 T i N aw WM. 2 6 9 0o 2 m 0 4 HUN- atenteol Nov. 1 i949 NITED STATES TENT OFFICE ELECTRIC DISCHARGE DEVICE OF THE INDICATOR TYPE Charles H. Bachman, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application October '7, 1944, Serial No. 557,579

12 Claims.

My invention relates to electric discharge devices and more particularly to improved electric discharge devices for indicating or measuring the magnitudes or relative magnitudes of electrical quantities.

Many electric discharge devices have been devised for indicating purposes which employ a fluorescent screen or electrode acted upon by a beam of electrons which is controlled in accordance with a quantity to be measured. The present invention releates to devices of this character and particularly to improvements in such devices which provide a better presentation of the indication from a visual standpoint, and which provide a satisfactory indication of the relative magnitudes of a plurality of quantities regardless of their absolute values.

It is an object of my invention to provide a new and improved indicating device of the electric discharge type.

It is another object of my invention to provide a new and improved electronic indicator for providing a visual indication of the relative magnitudes of a plurality of electrical quantities.

In the illustrated embodiment of my invention a source of electrons is provided by an elongated cylindrical cathode arranged to emit electrons in the general direction of an anode having an extended surface coated with fluorescent material. The portion of the anode which is acted upon by the electrons emitted is determined by the voltages impressed on a pair of deflecting members which are arranged end-to-end relatively close to the cathode and which deflect electron beams in accordance with the voltage impressed thereon. A suitable shield is provided behind or partially surrounding the cathode to concentrate the electrons in the area occupied by the fluorescent anode. If the voltages impressed on the deflecting plates are equal, the boundary of the fluorescent region is a straight line. If the voltages are unequal there is a break in the line at a point corresponding to the adjacent ends of the deflecting plates. Thus the boundary of the fluorescent region moves across the plates as the magnitudes of deflecting voltages increase with the difference in position of the two halves of the boundary depending upon the difference in magnitudes of the voltages. In another modification of my invention the deflecting plates are tapered and overlap each other with respect to the length of the cathodes so that the differences in voltages impressed on the deflecting members tend to rotate the boundaries of the fluorescent region on the anode. In still another modification, a member supported from the anode is provided with an elongated aperture for concentrating the electron beam at or near the plane of the aperture. The deflecting plates in this embodiment are arranged between this member and the cathode. This construction increases the sensitivity with the deflecting members operating on the electron beams passing through the aperture in much the same manner as a force applied to a lever having a fulcrum. located at a point corresponding to the aperture.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing in which Fig. 1 is a perspective view of the electrode assembly of one embodiment of my invention; Fig. 2 is an end view of the electrode arrangement of Fig. 1; Fig. 3 is a plan view of the anode of Fig. 1 showing the fluorescent pattern for a predetermined operating condition; Fig. 4 illustrates in general the mannor in which the electrode assembly of Fig. 1 may be mounted within an envelope; Fig. 5 is an end view of a modification; Fig. 6 is a plan view of the anode member of Fig. 5; Figs. 7 and 8 are perspective views of further modifications of the electrode assembly, and Fig. 9 is a schematic representation of an elementary circuit employing an electric discharge device having an electrode assembly like that illustrated in Fig. 1.

Referring now to Fig. 1 of the drawing, a source of electrons is provided by an elongated cylindrical cathode l which is arranged to emit electrons in the general direction of a rectangular anode member 2. The cathode is preferably coated with a material having good electron emitting properties such as compositions including alkaline earths or oxides thereof. The anode is coated with a suitable fluorescent material 3 and may be formed from a nickel plate having a coating of zinc orthosilicate which may be deposited thereon from a suspension of that material in a suitable liquid such as alcohol. The shield member 4 is located behind and above the cathode to assist in concentrating the emitted electrons on the surface of the anode member. As illustrated in Fig. 1, this shield may advantageously have a substantially right angular cross section with both sides of the shield extending obliquely with respect to the anode 2. In the interest of simplicity, no heater element has been shown for the cathode. It will be understood however that a suitable filament may be mounted within the cylinder l and in insulated relation with respect thereto. A pair of deflecting plates and 6 are arranged in end-to-end relation with respect to the length of the cathode and along the front edge of shield 4 for controlling the boundary of the electrons in the plane of the anode member 2. With the construction thus far described electrons emitted by the cathode l impinge upon the surface of the anode member 2 between the back edge I of the anode and a boundary line on the anode face determined by the magnitudes of the voltages impressed on the deflecting members 5 and 6. In Fig. 3 this is indicated by the line 8 having an offset portion 9 determined by the difference in magnitudes of the voltages impressed on deflecting members 5 and 6. The line shown in Fig. 3 results from impressing a negative voltage of greater magnitude on deflecting plate 5 than the magnitude of the voltage impressed in deflecting plate 6. As viewed in Fig. 3, the portion of the anode above line 8 will fluoresce while the portion below line 8 will be dark.

In Fig. 4 of the drawing the electrode structure in Fig. l is shown within a glass envelope II] of an electric discharge device. The electrodes are supported from a suitable stem press II by relatively rigid conductors I2I5 inclusive. As illustrated, conductor I2 supports the anode 2 and conductor I3 supports the shield member 4 which, in turn, supports cathode I by means of supporting conductors I6 arranged at opposite ends of the cathode. The deflecting plates 5 and 6 are supported by conductors I4 and I5, respectively. It will be well understood by those skilled in art that conductors 'I2I5 are connected to individual pins or prongs I! supported from a suitable insulating base I8 which is cemented or otherwise secured to the envelope of the discharge device. In Fig. 5 is illustrated an end view of an electrode assembly which is in general similar to the arrangement of Fig. 1 but which has been modified to produc a different type of indication. In Fig. 5 the cathode is arranged near or slightly beyond the back edge of the anode and the shielding plate, designated by the numeral I9, is shaped and positioned to concentrate the electrons at the front edge of the anode which is designated by the numeral 2. The front edge Of the anode is provided with an overhanging portion 20 supported in front of the anode to obscure any portion of the anode which fluoresces while the electrons are concentrated along the front edge of the anode. As the negative signal voltage is impressed on the deflecting plates 5 and 6 the electrons are moved to the left, as viewed in Fig 6, being bound on one side by the field produced by the deflecting plates 5 and 6 and on the other side by the action of the shield I9 and the space charge. The plate 6 is not visible in Figure 5 but is arranged in end-to-end relation with respect to the plate 5. The type of exhibit obtained with this construction is shown in Fig. 6 in which the fluorescent band 2| extends across the surface of the anode 2' with an offset portion 22 in the center resulting from the application of unequal voltages to the deflecting plates 5 and 6.

In some applications it is desirable to obtain an indication on the fluorescent screen which rotates as the difference in magnitudes of the voltages impressed on the deflecting plates increases. Such an arrangement is shown in Fig. '7 and is in general similar to the arrangement of Fig. l with corresponding parts being designated by the same reference numerals. In the arrangement shown in Fig. 7 the two deflecting plates 23 and. 24 are not arranged in end-to-end relation but are shaped to have a cross section which progressively diminishes from one end of the plate to the other. Each of the plates is substantially the same length as the cathode and anode and are arranged side by side witht he ends of small area oppositely located so that the total area of the two deflecting plates is substantially constant throughout the length of the cathode. In the particular form illustrated in Fig. 7, the deflecting plates 23 and 24 are triangular in shape. It will be appreciated that these plates may be tapered inaccordance with any curvilinear function to obtain the desired shape of the exhibit obtained on the fluorescent surface 3 of the anode 2. As illustrated in the drawing, the shield member 4' is provided with a portion 4" extending at right angles to the body of the shield 4 below the cathode I. This shield arrangement establishes a boundary line for the fluorescent area which is removed from the rear of the plate so that the exhibit on the anode tube takes the form of a fluorescent line which is rotated b variation of the voltages impressed 0n the deflecting members 23 and 24.

In Fig. 8 is shown a modification of m invention which is more sensitive than the arrangements of the modifications previously described. In the arrangement of Fig. 8, the cathode I and anode 2 are the same as illustrated in Fig. l. The shield member designated by the numeral 25 is of hollow rectangular cross section having a portion of the side toward the anode 2 cut away and with the sides of the shield member at a substantial angle with the plane of the anode. Spaced from the cathode and supported from the anode 2 by suitable supports 26 is a masking member 21 having an elongated aperture 2'! extending parallel to the cathode I. This type of structure results in the electron beam being drawn from the cathode in a converging manner so that the beam thickness becomes concentrated in a narrow region called the crossover. From this crossover, usually near the plane of member 21, the beam diverges. The aperture extends coextensively with plates 5 and 6. Deflecting plates 5 and 6 are arranged on one side of the beam between member 21 and cathode 2 and opposite the edge of the lower side 28 of the shield 25. In this arrangement the deflection of the electrons produced by voltages impressed on deflecting plates 5 and 6 is multiplied in much the same manner as the motion is multiplied by applying force to a lever close to the fulcrum. The distance between the member 27' and the anode member 2' being large compared with the distance between the deflecting plates and the member 27, the deflection obtained is greatly multiplied.

In Fig. 9 I have shown an elementary circuit illustrating the operation of an electric discharge device embodying my invention. In Fig. 8 the anode, cathode, and deflecting members have been designated by the same reference numerals as employed in Fig. 1 of the drawing. The anode is connected to a source of positive direct current voltage which may be in the order of to 300 volts. The cathode is connected to ground preferably through a source of biasing voltage illustrated by the battery 29 which maintains the cathode I at a slightly positive voltage with respect to the ground. One of the deflecting plates 5'is connected to a source of signal voltage 30 and the other deflecting plate 6 is connected to a source of reference voltage 3| or a second source of signal voltage. -With this arrangement so long as the voltages impressedon deflecting plates and 6 are equal the boundary 8.of-the fluorescent portion of the anode surface 2 will remain a straight line. If one of the voltages is of greater magnitude than the other, the line becomes offset at a point corresponding to the adjacent ends of the deflecting plates 5 and 6 as illustrated at -9 in; Fig. 3. From this description it is apparent that the line 8 will remain straight as long as the voltages impressed on deflecting plates 5 and t are equal regardless of their absolute magnitudes. This renders the discharge device particularly adapted for indicating the rel-- ative magnitudes of a plurality of quantities where variations in their absolute magnitudes are not of significance. From the foregoing detailed description of the particular embodiment of my invention and the operation thereof, it will be apparent that any number of deflecting plates may be employed and that discharge devices so constructed may be utilized for illuminating different portions of a fluorescent electrode in accordance with the magnitudes of any number of different electrical quantities. v

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifica'tions may be made without departing from my invention in its broader aspects and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising an elongated cathode, an anode having a fluorescent coating over an extended surface, shielding means adjacent said cathode for producing a space charge effect tending to concentrate the electrons emitted by said cathode on the surface of said anode, a pair of elongated deflecting members in end-to-end relation in a direction substantially parallel to said cathode, said deflecting members serving to confine said electrons to present a straight line boundary of the fluorescent portion of said anode structure when said deflecting members are energized by equal voltages and for providing a broken line boundary of the fluorescent portion of said anode when said deflecting members are energized by voltages of unequal mag-- nitude.

2. An electric discharge device comprising an elongated cathode, an anode having a fluorescent coating, shielding means adjacent said cathode for directing the electrons emitted by said cathode toward said anode, a pair of deflecting plates in end-to-end relation in a direction substantially parallel to said cathode, said deflecting plates serving to confine said electrons to present a straight line boundary of the fluorescent portion of said anode structure when said deflecting plates are energized by equal voltages and for providing a broken line boundary of the fluorescent portion of said anode when said deflecting plates are energized by voltages of unequal magnitude.

3. An electric discharge device comprising an elongated cathode, an anode including an extended surface having a fluorescent coating, a pair of deflecting electrodes in end-to-end relation in a direction substantially parallel to said cathode for controlling the flow of electrons from said cathode to said anode, said deflecting electrodes serving to confine said electrons on said anode structure to present a straight line boundary of the fluorescent portion of said anode structure when said deflecting electrodes are energized by equal voltages and for providing a broken line boundary of the fluorescent portion of said anode when said deflecting electrodes are energized by voltages of unequal magnitude.

4. An electric discharge device comprising an elongated cathode, an anode structure includin an extended surface, a pair of deflecting members in end-to-end relation in a direction substantially parallel'to said cathode for controlling the flow of electrons from said cathode to said anode, said deflecting members serving to confine said electrons impinging on said anode structure to present a straight line boundary on said anode structure when said deflecting members are energized by equal voltages and for providing a broken line boundary on said anode when said deflecting members are energized by voltages of unequal magnitude.

5. An electric discharge device comprising an elongated cathode and an anode including an extended planar surface, a shield including a planar portion extending behind said cathode and at an acute angle with the planar surface of said anode, said shield serving to direct electrons emitted from said cathode to the planar surface of said anode, and deflecting means adjacent the electron path between said anode and said cathode and in end-to-end relation in a direction parallel to said cathode for controlling the portion of the planar surface of said anode on which electrons emitted by said cathode impinge.

6. An electric discharge device comprising an elongated cathode, an anode including an extended planar portion having a fluorescent coating, a shield adjacent said cathode for directing the electrons emitted thereby to a restricted area of said anode, means overhanging said restricted area to obscure it from the sight of an observer, and electron deflecting means supported in endto-end and mutually insulated relation for deflecting said electrons from said restricted area to produce a luminous display depending upon the potential of said deflecting means.

7. An electric discharge device comprising a cathode, an anode including an extended planar portion having a fluorescent coating, a shield adjacent said cathode for directing the electrons emitted thereby to a restricted area of said cathode, and a pair of electron deflecting electrodes positioned in end-to-end and mutually insulated relation for producing a broken line display on the fluorescent coating of said anode when said electrodes are energized with voltages of unequal magnitudes.

8. An electric discharge device comprising an elongated cathode, an anode including an extended surface, and a pair of elongated deflecting plates each of substantially triangular shape positioned between said cathode and said anode for controlling the area of said anode on which electrons impinge, said plates being positioned side by side in an inverse relation and substantially parallel to the cathode so that the combined width of the plates is substantially constant as measured at different distances along the length thereof.

9. An electric discharge device comprising an elongated cathode, an anode including an extended surface, and a pair of elongated deflecting plates each of progressively varying width positioned between said cathode and said anode for controlling the area of said anode on which electrons emitted by said cathode impinge, said 7 plates: being; positioned side: by side. in. an inverserelation; and: substantially parallel to: the cathode so that the combined width of the plates is; substantially constant as measured at difierent distances along. the. length thereof.

10. An electric discharge device comprising an elongated cathode, an anodestructure having an extended. surface toward. said cathode, an electron masking: member positioned between said cathode: and said anode and relatively nearer to said cathode, said. member having an elongated aperture: extending substantially parallel to said cathode, and. a pair of electron deflecting members between said member'andsai'd cathode.

11., Anelectric discharge device comprising an elongated cathode, an anode structure having; a surface toward. said cathode coated with a fluorescent material, an: electron masking member positioned. between said cathode and said anode and relatively nearer to said cathode, said member having anelongated aperture extending substantially parallel: to said cathode, and a. pair of elongated electron deflecting plates positioned in endwtmend' relation: between said member and said cathode 12. An electric dischargedevice: comprising an elongated: cathode, an anode structure: having a surface toward said cathode coated with a. flucrescent material, an electron masking member positioned between said cathode and: said. anode and. relatively nearer'to said cathode, said. memher having an: elongated aperture extending: sub stantially parallel; to said cathode; a shield electrically connected with: said. cathode, said shield being shaped and: positioned. to partially enclose said cathode and: provided with an elongated opening generally in alignment with the aperture' in said member, and a. pair of elongatedelectron d'efiecting plates positioned in end-to-end relation in the direction of said aperture and be tween said member and said cathode;

CHARLES H. BACHM'AN.

REFERENCES- CITED The following references are of record in the file of this patent;

UNITED STATES. PATENTS 

